The leaders of Cambodia and Thailand agreed to a ceasefire on Monday effective midnight, in a bid to bring an end to their deadliest conflict in more than a decade after five days of fierce fighting.

Cambodia and Thailand have agreed to an “immediate and unconditional ceasefire” beginning at midnight local time (1 p.m. ET Monday), following days of clashes across the two countries’ disputed border.

U.S.-backed talks to end the border war, in which militaries have killed dozens of people and displaced hundreds of thousands, began on Monday in Malaysia.